lkml.org 
[lkml]   [2018]   [May]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH 1/6] firmware: permit LSMs and IMA to fail firmware sysfs fallback loading
From
Date
On Fri, 2018-05-04 at 00:02 +0000, Luis R. Rodriguez wrote:
> If you can add Andres Rodriguez <andresx7@gmail.com>, and Greg to your Cc list
> in the future patches that'd be appreciated.
>
> On Tue, May 01, 2018 at 09:48:18AM -0400, Mimi Zohar wrote:
> > Add an LSM hook prior to allowing firmware sysfs fallback loading.
> >
> > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> > Cc: Luis R. Rodriguez <mcgrof@suse.com>
> > Cc: David Howells <dhowells@redhat.com>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Matthew Garrett <mjg59@google.com>
> > ---
> > drivers/base/firmware_loader/fallback.c | 7 +++++++
> > include/linux/fs.h | 1 +
> > 2 files changed, 8 insertions(+)
> >
> > diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
> > index 31b5015b59fe..23d2af30474e 100644
> > --- a/drivers/base/firmware_loader/fallback.c
> > +++ b/drivers/base/firmware_loader/fallback.c
> > @@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags)
> >
> > static bool fw_run_sysfs_fallback(unsigned int opt_flags)
> > {
> > + int ret;
> > +
> > if (fw_fallback_config.ignore_sysfs_fallback) {
> > pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
> > return false;
> > @@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags)
> > if ((opt_flags & FW_OPT_NOFALLBACK))
> > return false;
> >
> > + /* Also permit LSMs and IMA to fail firmware sysfs fallback */
> > + ret = security_kernel_read_file(NULL, READING_FIRMWARE_FALLBACK);
> > + if (ret < 0)
> > + return ret;
> > +
> > return fw_force_sysfs_fallback(opt_flags);
> > }
> >
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 760d8da1b6c7..dc16a73c3d38 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -2810,6 +2810,7 @@ extern int do_pipe_flags(int *, int);
> > id(UNKNOWN, unknown) \
> > id(FIRMWARE, firmware) \
> > id(FIRMWARE_PREALLOC_BUFFER, firmware) \
> > + id(FIRMWARE_FALLBACK, firmware) \
>
> If you're going to add this perhaps FIRMWARE_FALLBACK_SYSFS as we may later
> get FIRMWARE_FALLBACK_EFI.

From an IMA signature verification perspective, both are buffer based.
 The file signature is stored as a security xattr.  Without a file
descriptor, the kernel cannot verify the firmware signature.

I don't have a problem with defining another enumeration.  Perhaps
other LSMs will want to be able to differentiate between sysfs and EFI
fallback methods.

Mimi

\
 
 \ /
  Last update: 2018-05-04 02:36    [W:0.068 / U:0.172 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site